TRA proposes to apply nuclear magnetic resonance imaging (MRI) techniques to investigate perfusion of blood in the organs. The aim of this project is to develop a model of perfusion and to establish procedures and formalisms for obtaining information about the specific permeability and void fraction of the vascular bed, permeability of the capillary endothelium, kinetic coefficients and extraction ratio, in addition to dispersion and mean bulk velocity. TRA proposes a statistical hydrodynamic model with a hydrodynamic dispersion coefficient and Darcy's velocity. This dispersion, although superficially similar to Brownian or turbulent diffusion, is physically different. Phase I work will investigate only the vascular bed, and the main focus will be on simulational and numerical work. Investigation of the tissue chamber and exchange kinetics will be undertaken in Phase II in which phase stylized phantom experiments will also be performed.